Fundamentals of Dark Matter - Ignacio Ferreras - 2025

This textbook introduces the evidence, theories, and scientific debates surrounding dark matter. ⭐

It explains how astronomers infer unseen mass from galaxies, galaxy clusters, cosmology, and particle physics, while also examining alternative explanations such as modified theories of gravity.

1. Dark Matter Exists Because Gravity Appears Stronger Than Visible Matter Can Explain

2. Galaxy Rotation Curves Provide Some of the Strongest Evidence

3. Galaxy Clusters Also Contain Large Amounts of Missing Mass

4. Gravitational Lensing Reveals Invisible Mass

5. Dark Matter Helps Build the Structure of the Universe

6. Cosmology Suggests Dark Matter Is a Major Part of the Universe

7. Scientists Are Searching for the Particle That Makes Up Dark Matter

8. Dark Matter Might Not Exist—Maybe Our Understanding of Gravity Is Incomplete

⭐ Star Facts

⭐ Dark matter was first proposed in the 1930s, yet scientists still have not directly detected it.

⭐ The evidence for dark matter comes entirely from its gravitational effects, not from seeing it directly.

⭐ Stars on the edges of galaxies move much faster than visible matter alone can explain.

⭐ Galaxies are thought to sit inside enormous dark matter halos that extend far beyond their visible stars and gas.

⭐ The first major evidence for dark matter came from galaxy clusters, where galaxies were moving too fast to be held together by visible matter alone.

⭐ Gravity bends light, and measurements of this bending reveal much more mass than telescopes can see.

⭐ Dark matter appears to make up about five times more matter than all the stars, planets, gas, and dust combined.

⭐ Scientists have proposed many dark matter particles, including WIMPs and axions, but none have been confirmed.